The present invention relates in general to a frequency based cartridge detection system. Particularly, the present invention relates to a detection system for identifying a disk for use in a disk drive. More particularly, the present invention has a source of irradiance for irradiating a marker, and a detector for detecting light emitted from the marker. Even more particularly, the present invention relates to detecting the presence of the correct disk in the disk drive by determining a frequency domain response of the light emitted from the marker. The frequency domain response may be either a phase response, an amplitude response, or both.
Disk drives for receiving removable disk cartridges, including conventional 3.5 inch floppy disk drives, must have some mechanism for detecting the insertion or presence of a disk cartridge in the drive. The actuator that carries the recording heads of the disk drive across the recording surfaces of the disk should not be allowed to move unless the presence of an appropriate disk cartridge which is non-drive damaging is detected. The removability feature requires that the disk drive have a cartridge insertion opening into which foreign objects can be inserted. If these objects physically engage the drive as a legitimate cartridge would, then the heads could be loaded onto or into the foreign object, thereby destroying the drive. Also, the spindle motor of the disk drive will be activated by a falsely detected foreign object, thereby generating particle debris. In the prior art, mechanical switches are typically employed to detect the presence of a disk cartridge within the drive. Such switches are typically positioned such that when a disk cartridge is inserted fully into the drive, the cartridge contacts the switch, thereby providing an indication that the disk cartridge is present.
xe2x80x9cRETROREFLECTIVE MARKER FOR DATA STORAGE CARTRIDGExe2x80x9d, U.S. Pat. No. 5,638,228, to Thomas, III, describes the reflection of a highly concentrated quasi circular lobe of light whose spread on reflection is captured by the aperture of a phototransistor in close proximity to a light-emitting diode (LED). This emitter/detector pair is in the drive and a retroreflective array is on the cartridge. The desired light lobe size is provided by the geometric size of the retroreflector array elements relative to the spacing of the emitter and the detector in the drive. Due to this physical size matching and the fact that retroreflectors are used, this marker on the cartridge is quite insensitive to cartridge tilt and distance from the emitter/detector pair in the drive. This patent is incorporated herein by reference.
Recently, very small mini-cartridges have been developed for use in miniature disc drives. These mini-drives are incorporated into hand-held devices such as digital cameras, electronic books, global positioning systems, cellular phones and the like. xe2x80x9cINTERCHANGEABLE CARTRIDGE DATA STORAGE SYSTEM FOR DEVICES PERFORMING DIVERSE FUNCTIONSxe2x80x9d, Ser. No. 08/746,085, filed Nov. 6, 1996, Edwards, et al., describes such mini-cartridges, mini-drives, and hand-held devices. This application is incorporated herein by reference.
As disk storage products become smaller and smaller, the need for a cartridge marker of thinner physical size is required. In very thin disk drives where the distance between the cartridge marker and the optical sensing device is very small (e.g., 1 mm), the inherent reflective gain mechanism obtained with a retroreflector over a diffuse or specular reflector is lost. Holographic directional light control is possible, but due to the very small working distances the ability for false engagement of the drive is significantly increased with that approach.
The ability to discriminate between cartridge types after insertion into a data storage device but prior to putting the read/write heads on the recording media is of significant value and utility. Principally this utility comes from the ability to detect the difference between various capacities or generations of data storage cartridges in a downward media compatible data storage drive. This discrimination capability allows for drive/media specific adjustments to be made such as media rotation rate, data channel rates, location of Z track for initial seeking, or even mechanical adjustment in the drive like the active engagement of new crash stop locations. The ability of a disk drive to predetermine the type/generation of data storage cartridge inserted into it prior to enabling the spin-up and engagement of read/write elements also provides the drive system designer with new possibilities for cross-platform interchangeability.
A xe2x80x9ccaddyxe2x80x9d cartridge, as mentioned in the aforementioned Edwards, et al. application, provides cross drive platform compatibility, for example between mini-cartridges and personal computer cartridges. The ability to recognize the installation of a xe2x80x9ccaddyxe2x80x9d into the drive prior to spinning up of the xe2x80x9ccaddyxe2x80x9d and loading of heads is necessary. Again rotational speed adjustments, Z track location information, data channel rate and crash stop/ID and OD data track location information must be determined prior to read/write head loading. This invention provides a solution of these problems also.
Another problem associated with the detection of LED light reflected from any reflective material is the occurrence of illuminance hot spots or structure in the LED output which often results in uneven illumination of the cartridge marker. Reflective cartridge markers can also become faded, scratched, or soiled. These factors combine to make the amplitude of the detected light signal highly variable.
Recently, in various industries such as the distribution industry, phosphors have been used in the control of goods by means of bar codes, and furthermore, bar codes are printed on various prepaid cards and passing cards, and these bar codes are read by optical reading apparatuses such as scanners to perform the desired actions. Moreover, various attempts have been made to apply forgery preventive means to credit cards and prepaid cards or to detect forged cards. For example, the marks such as bar codes are printed with an ink containing a phosphor by offset printing or by using an ink ribbon to form latent image marks. The latent image marks are irradiated with a semiconductor laser beam to excite the phosphor and the light emitted from the phosphor is received to read the bar code information by an optical reading apparatus. These techniques use the content or spectral shift from the irradiating light source for identification.
More recently, phosphors have been used in the disk drive industry for the identification and discrimination of disk and disk cartridges in disk data storage drives. xe2x80x9cLATENT ILLUMINANCE DISCRIMINATION MARKER FOR DATA STORAGE CARTRIDGESxe2x80x9d, Ser. No. 09/161,007, filed Sep. 25, 1998, Thomas III, et al., describes a system for identifying and discriminating removable data storage cartridges and a data storage drive for receiving the cartridge. In addition, xe2x80x9cLATENT IRRADIANCE DISCRIMINATION METHOD AND MARKER SYSTEM FOR CARTRIDGELESS DATA STORAGE DISKSxe2x80x9d, Ser. No. 09/160,811, filed on Sep. 25, 1998, Krieger et al., describes a phosphor marker for discriminating a cartridgeless type disk object that has been inserted into a disk drive. The systems of each of the above relate to the detection of the presence of the phosphor marker by measuring the time required for the radiated light from the marker to decay from one level to another level after the incident light from a light source is removed (e.g., the decay rate). Although the decay rate may provide the basis for discriminating an object that has been inserted into a disk drive, this approach provides an electronically complicated method of detecting the presence of the phosphor marker.
Although the art of detecting and discriminating between data storage cartridges is well developed, there remain some problems inherent in this technology, particularly in providing an electronically simple system that is accurate and inexpensive. Therefore, a need exists for a marker and detection system that produces reliable detection and discrimination between data storage cartridges under varying gain and marker spacings.
The present invention is directed to a data storage disk having a latent illuminance discrimination marker for determining whether the data storage disk is suitable for use in a disk drive. A light source illuminates the marker and the marker emits illuminance, preferably as phosphorescence. A detector detects the emitted illuminance, and a predetermined characteristic of the marker in the frequency domain is determined in order to validate the inserted disk. The frequency domain response may be either a phase response, an amplitude response, or both. The frequency domain response provides identification of different types or generations of data storage disks or provides a secure keying mechanism for authorized access to proprietary software.
According to one aspect of the present invention, the data storage drive has a source of irradiance at an irradiance wavelength and a detector of irradiance for determining whether a disk is suitable for use in a disk drive. The disk includes a body having a data storage medium and a marker on the body. The marker is adapted to receive irradiance from the source and emit irradiance toward the detector for detection of a frequency response of the emitted irradiance which thereby identifies the disk as being suitable for use in the drive.
In accordance with a further aspect of the present invention, the frequency response is a phase response. The phase response preferably includes a phase shift between the irradiated signal and the re-radiated signal. The phase shift is measured as a lag of the re-radiated signal from the irradiated signal. The marker is swept over frequency and the phase shift between the injected signal and the re-radiated signal is measured. The resulting phase response curve can be compared to an expected response to determine if the disk is valid.
In accordance with a further aspect of the present invention, the frequency domain response is an amplitude response. The amplitude response preferably includes a differential measurement in a peak amplitude of the irradiated signal and the re-radiated signal. The marker is swept over frequency and the amplitude of the re-radiated signal is measured. The resulting value is compared against an expected response to determine if the inserted disk is valid.
In accordance with a further aspect of the present invention, the frequency domain response is both a phase response and an amplitude response.
In a further embodiment within the scope of the present invention, a system is provided for determining whether the cartridge is suitable for use in the data storage drive. The system includes a data storage drive having a source of irradiance at an irradiance wavelength, a detector of irradiance, and a measurement mechanism for measuring a response characteristic of the emitted irradiance in the frequency domain which thereby identifies the cartridge as being suitable for use in the drive. The system further includes a disk for insertion into the data storage drive. The disk includes a body having a data storage medium, and a marker on the body. The marker receives irradiance from the source and emits irradiance toward the detector for detection one of a phase response, an amplitude response, or both of the emitted irradiance in the frequency domain which thereby identifies the cartridge as being suitable for use in the drive.
According to further aspects of the invention, the measurement mechanism preferably includes a phase shift oscillator. The marker can be used as the frequency-controlling element in the phase shift oscillator. The system also includes a feedback loop which oscillates in response to the present of a marker with a predetermined phase response. A second order high pass filter can be provided and the feedback system oscillates at a frequency where the combined phase shift presented by the amplifier, the marker, and the second order high pass filter reaches about 360 degrees.
According to further aspects of the invention, the measurement mechanism includes a swept frequency source. The marker is swept over the frequency source to excite the marker and the detector measures at least one of the phase response and the amplitude response. The swept frequency source can be a frequency controllable oscillator.
According to further aspects of the invention, the data storage drive includes a noise source which modulates a light source and irradiates the marker. The noise source is preferably white gaussian noise.
The foregoing and other aspects of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.